Well testing apparatus



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W rflFf Aug. 14, 1951 L. E. ELKINS f WELL TESTING APPARATUS 6Sheets-Sheet 6 Filed Jan. 15, 1945 Patented Aug. 14, 1951 WELL TESTINGAPPARATUS Lloyd E. Elkins, Tulsa, Okla., assignor to Stanclind Oil andGas Company, Tulsa, Okla., a corporation of Delaware Application January15, 1945, Serial No. 572,878

14 Claims.

This invention relates to the testing of wells and more particularly tolocating the fluid-producing strata in oil and gas wells and determiningthe nature of the fluids produced. It is especially suitable for thetesting of wells producing several different fluids simultaneously, suchas gas, oil, and water or brine.

Various methods have been proposed for locating the permeable,fluid-producing zones of wells, particularly those producing brine. Inmany of these methods it is necessary to condition the well beforetesting by providing a column of fluid of known characteristics whichare altered in a detectable way when fluid enters from the formation.This conditioning of a well is usually expensive, time-consuming, anduncertain, for the well must be shut in, circulatingv equipment andconditioning fluid must be provided, and in many instances an unknownamount of the conditioning fluid may penetrate the formations andsubsequently mask the true nature of the fluids naturally producedthereby. Also the technique of handling a. well fllled with conditioningfluid is often exceedingly delicate. Too sudden pressure changes mayupset the hydrostatic fluid balance and cause a rush of-fluid either outof or into the formations so as to interfere with observation of thesignificant eifects. These efiects are, at best, transitory and subjectto being disturbed by the process of observing them.

In other well-known methods of testing formations to determine theirfluid-producing charac ter, the section of the formation under test isfirst sealed off by packers or similar means, and fluids are thenwithdrawn from this sealed-01f section for identification or'analysis.Obviously, if the seal is imperfect, extraneous fluids may enter andmingle with the test fluids so as to give confusing results. It isextremely diflicult to detect such contamination without the use ofspecial precautions. In addition, if several strata in a producing zoneare to be tested individually, it is usually necessary that the tubingand testing equipment he completely withdrawn after the testing of eachsuch stratum. This adds considerably to the time and expense of makingthe tests and also results in an extended and undesirable interruptionof the well production. Further, since a substantial pressuredifferential is ordinarily created between the sealed-off test sectionand the remainder of the producing zone, the design of packers towithstand this pressure diiferential and prevent leakage past the sealconstitutes a problem that is often difllcult of solution.

For the testing of wells to determine their fluidproducingcharacteristics I have now devised an apparatus which overcomes most orall of these disadvantages. This testing apparatus is applicable to alltypes of wells without the need of any preliminary conditioning of thewell fluids or prolonged interruption of the well production. Severaladjacent strata in a producing zone can be individually tested at asingle setting of the apparatus, and due to the fact that all parts ofthe producing zone are at all times in balanced equilibrium, the packersor elements designed to segregate production are not subject tomeasurable pressure diiferentials, and therefore the danger ofcontamination of fluid from one section of the zone by fluids from othersections is eliminated.

It is, therefore, a primary object of my invention to provide a noveland improved apparatus for determining the location and nature of fluidentries into wells. Another object is to provide an apparatus fortesting a well causing a minimum of interference with the production ofthe well, and particularly an apparatus which requires no extendedinterruption of the "well production for conditioning and testing thewell fluids. A further object is to provide an apparatus for testinga'well while it is producing at any desired rate, or at different rates,and either over a short or an extended period of time. A

still further object is to provide a test apparatus in which the well iseasily controlled, and in which pressure differentials throughout theproducing section are kept low so that some of the usual causes of errorare minimized or completely eliminated. Another object is to provide anapparatus for making a complete determination of the fluids andfluid-producing character of several adjacent well strata at a singlelowering of the testing aparatus into the well. A further object is toprovide an apparatus for determining the relative fluid permeability ofeach individual pay section as compared with that of other pay sectionsopen to the well. Other and more detailed objects, uses, and advantagesof the invention will become apparent as the description thereofproceeds.

In the appended drawings forming a part of this specification variousspecific embodiments of the invention are shown illustrating itsapplication to the testing of wells. It should be kept in mind, however,that these drawings are for the purpose of illustration only, and thatthe invention is not limited solely to the employment of the exactapparatus and methods there dis- 3 closed. In these drawings, in whichthe same reference numeral in different figures is used to indicate thesame or analogous parts;

Figure 1 represents in diagrammatic form a cross section of the earthpenetrated by a well amuse from each individual section. Instead.Pressure differentials throughout the whole test zone are kept so smallthat even if the isolating seal between adjacent sections is notperfect, only a showing one ,embodiment of the invention in testingposition in the well;

Figure 2 is a cross section of one of the sealing members of theapparatus of Figure 1;

Figure 3 isa cross section showing details of a valve used in theembodiment of Figure 1;

negligible amount of fluid will leak past it.

'1' Referring now to Figure 1, there is shown I drilled from the surface20 a well it, which may suitably have been equipped with a casing I2Figure 4 is a wiring diagram suitable for the cemented above theproducing section at 23. Well 2i normally will be equipped with a tubing24 and some means for controllably producing well fluids through thistubing such as equipment for flowing, pumping, swabbing. gas lifting, orthe like. By way of illustration only, an insert-type pump is showngenerally at II. The surface equipment may. consist of the usual tubinghead and stuffing box assembly 21 together with tubing elevator 28coupled to a hoist 2! (not shown in detail) for raising or lowering thetube Figures 8 and 9 are, respectively, longitudinal and transversecross sections through a fluorescence type of identifier unit;

Figures 10 and 11 are, respectively, longitudinal and transverse crosssections through a lightabsorption type of identifler unit:

Figure 12 is a diagrammatic cross section of a well showing analternative embodiment ofthe invention in testing position therein;

Figure 13 isan elevation of one of the sealing or packer members shownin Figure 12;

Figure 14 is a diagrammatic cross section of a well into which is beinglowered a third embodiment of the invention, including means forcarrying out relative fluid-permeability measurements on thewell'formations;

Figure 15 is a diagrammatic cross section showing certain details of oneof the units making up the apparatus of Figure 14;

Figure 16 is a wiring diagram of the embodiment of Figur 14;

Figure 17 is a diagrammatic cross section of a well showing theembodiment of Figure 14 .in testing position therein with the packer orsealing members expanded.

ing. Below the tubing seat I! forinsert pump is a tubular member Iihaving openings at 32,

II, II, 36. Fixed to member 3i between each of these openings aresealing or packer members ll, 31, I, each of which may consist of anexpansible resilient sleeve flxed at either end to member ll. At thelower end of member I is a pump consisting of cylinder and piston Inormally urged In brief, this invention comprises an appara- I tus forsubdividing the portion of the well to be tested. into a number ofsections more or less isolated from each other and then identifying inplace the fluids produced at each section before they become mixed withfluids produced at other sections. In other words, as fluids enter thewell sure equilibrium with all the others, since, after being identifiedor qualified as to type, the fluids from each section are connected andflow into a common stream within the tubing or flow string in the well.Thus, there is little or no tendency for fluid to migrate from oneisolated'section to another by leaking past the packer or sealingelements. This is in contradistinction to those usual methods in whichan effort is made to seal or! completely the section to be tested, inthat here no significant pressure differentials are created which mightcause fluid migrationto or iiii being near the center of the sleeve.

downward by a spring ll. Piston rod 42, of a length which may be changedto suit particular well conditions, is terminatedln a foot piece 0 atits lower end. Connected to and communicating with cylinder 39 is avalve assembly 44 capable of performing several functions, which willsubsequently be more fully described in connection with Figure 3. Fromthe outlet of valve assembly extends a tube 45 with branches opening atI, 41, u to the inside of packer members l6, I1, 38, respectively; Fixedto tubular member II at points near the openings 32, II, II, ll arefluid-identifying units ll, 50, ii, I! which may be any one or more ofseveral suitable types to be laterdescribed. For the present it issufficientto state that almost any device capable of measuring orresponding to a quality or property characterizing the fluids in whichit is immersed might be adapted to this use. Insulated electrical leads53, El, 55, I6 connect each of these fluididentifying units respectivelyto a switching unit I1, which is not shown in detail but which maysuitably consist of a fluid-tight annular casing connected between thebottom end of tubing string 24 and the upper end of member ii, and inwhich is a rotary multipoint selector switch operated slowly throughgearing by a small A. 0. electric motor. Insulated lead 58 extends fromone point of the rotary switch in switching unit I I! to an operatingsolenoid in valve assembly 44.

From unit 51 an insulated two-conductor cable I] extends upward to thesurface electrical equip- 60.

menta v i In Figure 2 is shown in more detail the. construction of oneof the packing members 81 of Figure 1. A resilient sleeve 00 is clampedtightly to tubing member ii at each end by metal bands ll, 02. It'willbe noted that sleeve 60 has a greater wall thickness at its ends thanWith this construction it is apparent that the application of fluidpressure through tube 45 and branch opening 41 will expand sleeve 6|more rapidly at the center than at the ends and thus will insure itsmaking contact with and sealing a ainst the walls of a well havingirregularities or varying diameters at different points.

Referring now to Figure 3,.there are shown the deslgmdetails of a valveassembly 04 which will perforni*., the functions required in thisembodiment. This consists of a central body member 03 havingfa sideoutlet 04 adapted to be connected to tube 40 of Figure 2. At the loweror inlet end of valve body is a check valve consisting of a seat 05,ball 00, and retainer 61.

Closing the upper end of valve member 00 is a relief valve consisting ofseat 00 and ball 00 held down by a compression spring 10. The force ofspring 10 can be adjusted as needed by a perforated abutting screw II.In the sides of valve body member 00 are ports 12 which open to a spacebetween packing cup washers I3, 14, fixed to a ferromagnetic sleeve I!by a ferromagnetic cap member 10 threaded thereto. Packing cup washersI3, 14 are held apart by a spacer II. Sleeve member I carrying packingwashers I3, I4 is slidable on valve member 00, and is normally held in aposition closing ports I2 by a spring forcing it against an abuttingring I0. Surrounding the lower end of sleeve 10 and cap I0 is a solenoid00 having a coil winding with one end grounded and the other end 7connected by insulated lead is to a contact in switching unit 51 asheretofore described inconnection with Figure 1. Upon inspection it willbe seen that by passing a current through solenoid 00 ferromagnetic cap10 and sleeve IE will be drawn downwardly, compressing spring l0, anduncovering ports I2. Fluid under pressure can then escape through ports12, an annular space 0| between sleeve I0 and valve body 03, and outslots at 02, or through ports 00 and the hole in perforated abuttingscrew Through a stumng box 04 shown in Figure 1 cable 00 is brought outto suitable surface electrical equipment. This may include a source ofA. C. power 00 and switch 00 in series connected between tubing 24 andone conductor of cable 00, while a switch 01 and battery 00, in serieswith a recorder comprising units 00 and 00 are connected between tubingand the.

below are fixed to the tubular member 0i. Electrically connected betweentubing 20 and the power lead of cable 00 is an A. C. electric motor I00which, through mechanical gearing (not shown), drives slowly the movingcontactor IOI of a rotary selector switch I02. contactor III isconnected to the recording circuit lead of cable ll, while theindividual points of switch I02 are connected by insulated leads l0, 04.ll, 00 to identifier units 40. I0, ll, 02, here shown asfluid-conductivity cells. but which may be any other suitable type offluid-identifying unit. One contact point I 03 may advantageously beconnected to tubing .24 through a known resistor I 04. which then servesboth as a means of correlating the switch contactor position with therecord trace and as a means of calibrating the resistance of therecording circuit. Another contact point I00 may suitably be connectedthrough a time delay relay I00 to the insulated lead 50 extending tosolenoid 00 of valve assembly H. The delay of relay I00 is so adjustedthat its contacts will not close during the normal time interval thatcontactor III is on point I00 as the switch is being rotated by motorI00.

A suitable recorder for use with this invention is the Westinghouse TypeGH Pilotel Recorder which consists of an amplifier unit 09 (which may ormay not be used, as required) and a pen-driving chart-moving unit 90.This instrument is adapted to trace on a moving chart strip a continuousline representing the variations with time of any desired electricalquantity such as current or voltage.

Upon inspection it will be seen that with this circuit arrangement boththe switching and recording operations are completely at the control ofan observer at the surface, since by closing either or both of switches06, 01. the rotary selector switch I02 can be actuated at will, or areading either taken on an identifier unit or omitted as desired. Itshould be noted that due to the presence of relay I06, it is practicallyimpossible to actuate solenoid 00 of valve 40 (Fig. 3) inadvertently,since switch-driving motor I00 must be completely stopped with contactorIII on point I05 for an appreciable time before the contacts of relayI00 close. Further, from the fact that one of the points of switch I 02is not utilized, it should be kept in mind that the use of four suchunits in Figures 1 and 4 is illustrative only, and more or fewer will beused when appropriate.

In Figure 5 is shown the apparatus of Figure l with the packers orsealing members retracted as it is being raised or lowered in a well. Inoperation this apparatus is lowered until foot member 43 strikes bottom.the length of piston .rod 42 having been previously adjusted so as toplace member II and its associated equipment at the proper level. Thenby alternately raising and lowering the tubing 24 a few inches, cylinder00 and piston 40 are reciprocated and through valve 44 and tubing 45inflate the resilient packer sleeves 00, 31, 30. The compression ofreliefvalve spring I0 is adjusted so that the pressure inside packersleeves I0, 01, 00 will be sufficient to inflate them into flrm contactwith the walls of the hole but insufllcient to rupture them in. theevent the pump is operated longer than necessary. After the packersleeves 30, 01, 00 have been inflated, well II is caused to producefluids either by opening a control or choke valve ifthe well is aflowing one, introducing high pressure as from the annulus into thefluid in the tubing in case the well is equipped for gas lifting, or byinserting and operating pump 20. By whatever method is appropriate,fluid is caused or allowed to enter the well from the formations. passthrough tubing inlets II, 00, 04. II and be withdrawn from the wellthrough tubing 00. Closing of switch 00 permits power to be transmittedto motor I00, which rotates contactor III.

Then with switch 01 also closed, readings of identifier units 40, 50,II. 02 may be transmitted to recorder 00 in succession. As well II isproduced, fluids from the formations enter the spaces between andoutside of resilient packer sleeves 30, 01. 00 and travel to each of thetubing open! ings communicating-therewith. After a period of time,fluids originally present in the spaces between sleeves 08, 01, 00 willhave been replaced by fluids from the formations at thecorrespondobtained as to the fluids produced above 1 below the seal.

ing level, and a reading on each identifier unit will then be trulyindicative of the nature of these latter fluids.

Since openings 32, 23, 30, 35 communicate with all of the sealed-offsections, it will be seen that there is little or no tendency to createlarge pressure differentials acrossv any packer seal and thereby causeleakage past it. Normally the rate at which the well is produced and thetime during which the production is continued should be sufficient toinsure that the fluids fllling all the spaces around packer sleeves 36,31, 38 eventually are the same as in the formations outside.

What is a proper rate and period of time will very from well to welldepending, in part at least, upon the permeability of the formationsexposed. Thus, it is apparent that a much longer time at a given'ratewill be required for suilicient fluid to enter from impermeableformations to displace those fluids originally surrounding theidentifying unit than is required where the formations are highlypermeable. If knowledge of the relative permeability of all the wellformations is available, it can be used to great advantage in arrivingat the optimum rate and duration of testing.

It is also possible to estimate when the well has been producing for asumcient length of time by observing the changes with time of the fluidssurrounding or When no further changes are observed at a given unit, itis then safe to assume that the fluids surrounding it are trulyrepresentative of those in the surrounding formations.

Although for illustrative purposes Figure 1 shows subdividing the wellinto four test sections, this number will be varied to suit individualwell conditions and to obtain the information needed. For maximumdefinition of fluidproducing strata the test portion of the well wouldbe divided up into many short sections, while for other purposesadequate information could be obtained using only a few and longersections. To go to the extreme, only one such packer might be used, andby providing ports both above and below it information could b:

While only one such unit is illustrated in Figure 1, two or morediiferent types of fluid-identifying units may be used simultaneously atthe 1 same'tubing open'ng, depending on the completeness of theinformation which is desired. In Figures 6 and '7 is shown a unit foridentifying fluids by their electrical conductivity. Covering theopening 32 in tubing member 3| is a hood I09, insideo'f which is aninsulated metal plate electrode I I set in a block I I I of suitableinsulating mater al such as, Bakelite. An insulated lead 53 brought outthrough the wall of tubing 3i and insulating block III connectselectrode IIO with a terminal in switching unit 51 shown in Figures 1,4, and 5. It will be apparent that with the I applicat on of voltage toelectrode IIO a current will flow between it and hood I03, depending onthe electrical conductivity of the intervcning fluids being drawn totubing inlet 32. Since the electrical conductivity of water or brine asfound in oil wells is normally widely different from that of thehydrocarbons found therein, this unit is particularly adapted todifferentiating between these substances.

In Figures 3 and 9 I have shown a fluid-identilying unit which may beused to detect the presence of crude oil as differentiated from gas andwater. This may suitably comprise a fluid-tight passing each identifyingunit.

8 housing I I2 placed adjacent opening 32 in tubing 3| and surrounded bya hood or shield I I4. In the wall of housing H3 is set a transparentdisk II5 held. in place by threaded ring H6 and sealed by a suitablethixotropic or semi-fluid sealing medium placed around its outer edge soas to prevent passage of fluid. Inside of housing H3 is an ultravoiletlight source III and a photocell 8 with filters H9 and I interposed. Ashield I2I prevents light from source III from falling directly onphotocell II8. Filter II! is one which preferably passes onlyultraviolet light and absorbs or cuts off visible light. Transparentdisk II5 should preferably be of quartz or a type of glass which willtransmit ultraviolet light. Filter I20 is one which will excludeultraviolet light while transmitting visible light. Insulated conductorI22 passing through the wall of member 3| and housing II3 connectsphotocell IIB with one point of the selector switch in unit 51 (Fig. lor 4), while a similar lead I23 connects light source III with the leadby which motor I00 is supplied with A. C. power. It will be seen that inoperation this unit will indicate the presence of any liqu.d capable ofiiuorescing as it moves past disk II5 to reach opening 32. Sincepractically all crude oils fiuoresce strongly in ultraviolet light, thisunit is a sensitive detector for them.

In F.gures 1:1 and i1 is illustrated an alternative identifying unitsuitab-e for identifying fluids according to their ability to transm-tor absorb light. Opening 32 in tubing 3i is here covered by a casing I20forming part of two fluid-tight housings I25, I26 contahing light sourceI21 and photocell I28 respectively. In the Walls of these housingsfacing each other are set glass disks I29, I30 held in place by threadedrings I3I, I32. It will be understood that a suitable thixotropicsealing'medium surrounds glass disks I23, I30 to prevent flu d fromentering the housings. Insulated lead I33 connects photocell I28 to aselector switch point in unit 51 (Fig. 1), while lead I34 supplies powerto light source IZ'I from one side of A. C. motor I30 (Fig. 4) in thesame way as with the unit of Figures 8 and 9. With this arrangement, inorder for fluids to reach opening 32 they must pass between glass disksI29, I30 50 that their light-absorbing properties can be measured.Although no special wavelength of light is specfled, of which theabsorption is to be measured in passing through the fluid between disksI20, I30, it will be apparent that by the interposing of proper filters,particular bands of wax elengths which are strongly absorbed by thefluids to be detected may be used and the selectivty of the unitincreased accordingly.

While I have described in some detail certain convenient types offluid-identifying units for use in this invention, many others might bedevised which would work equally well by differentiating between othercharacteristics of the well fluids. Thus, it would be possible todistingu'sh between gas, oil, and water on the basis of viscosity,specific gravity, heat conductivity, acoustic wave velocity, and manyother properties, and means for carrying out such measurement will occurreadily to those skilled in the art.

For use in wells having walls that are fairly regular and uniform I haveshown in Figure 12 an embodiment of the invention having a packer orsealing means different from and somewhat simnler in operation than thatshown in Figure 2. In Figure 12 it will be noted that tubing member 3|is closed at the lower end and provided with inlet ports 32. 33, I4, 35as before. Al-

though the identifier units 49, 50, I, 52 could be mounted as in Figure1 and 5, they are here situated immediately adjacent the openings andshields I35, I35, I31, I38 are placed over them so that fluids in orderto get to openings 32, 33, 34, 35 must pass close by or through theidentifying units. The packer or sealing members I39, I40, I H are heremade of some resilient material, such as a synthetic rubber which is oilresistant. As shown in more detail in Figure 13, each packer device I40is formed of many thin flexible disks I42 of varying diameters,preferably tapered in thickness from the tubing radially out towards theouter edge which may be very thin. It will be apparent that uponlowering this device into a well, there will always be one or more ofthe flexible disks of the right diameter to close 011. the well bypressure against its walls. This will be aided by the pressure of disksof larger diameter, since the tapered construction will confine theflexing of each disk to a point near the wall of the well rather thanallowing the disk to buckle near its base. Also, adjacent disks willtend to support each other and press their edges into firm contact withthe sides of the well.

The operation of this embodiment is similar to that of Figures 1 and 5except that in this case no inflation of the packer devices is necessaryand all that is required is to lower the device in the well and startthe well to producing, such as by opening a flow valve, admittinglifting gas. or in serting a pump on seat 30 and operating it. Thewiring diagram of Figure 4 is applicable here with the only modificationthat the relay I05 and lead 58 to solenoid 80 can be omitted and theswitch point I05 used for an identifying unit or left blank if notneeded. Likewise any desired type of identifying unit may be used, aloneor in combination with others. That is. two different types of unit maybe used at the same tubing opening, or a different type of unit orcombination of units could be used at different tubing openings. Forexample, in wells where it is known that water enter only at the bottomand gas near the top of the producing zone, the, units near the bottomof the testing unit might be those particularly adapted todifferentiating between water and oil, while those at the top woulddifferentiate between gas and oil.

It should be noted that the placement of the identifying units withinhoods or shields which force the fluids to flow by them to reach thetubing openings could be used advantageously on the apparatus of Figures1 and 5, and such modifications of that embodiment are considered withinthe scope of this invention.

In Figure 14 I have illustrated another modification of my inventionwhich provides for making a more complete survey of the well than doeither of the embodiments heretofore described. In this the tubingmember 3I is made up of individual sections such as I43, I44 and inletports are provided at I45, I45, I41, which are normally closed when theapparatus is run into the well. The upper ports I45 are, located nearinsert pump seat 30 and are closed by a sliding sleeve-valve arrangementconsisting of a sleeve member I49 urged upward by a coil spring I50which rests on a ledge I5I inside tubing 24. A depending hood or shieldI52 fixed to the tubing above ports I45 provides that fluids enteringthese ports must pass identifier units I53, I54.

A complete single apparatus unit, of which any desired number can beconnected together to form the testing apparatus, is shown in moredetail in Figure 15. This consists of the section of tubing I43 havingports I45, and fixed thereon a resilient umbrella-shaped packer sleeve Isecured at its upper end to tubing I43 by a clamping band I56 andnormally forced open at the bottom by steel leaf springs I51. 'When thedevice is run in the well, the steel springs I 51 and resilient packersleeve I55are held away from the wall in retracted position by hookingthe projecting ends I58 of springs I51 under a collar hook member I59,forming a part of a tubular sleeve I50, which may be an integral part ofa housing I5I surrounding ports I45 and identifier unit I52, I53. Thelower end of housing I5I is of the same diameter a sleeve portion I50 toform a guide for the end of tubing section I43 and is threadedly coupledto a tubing section I44 forming a part of the next lower packer sectioncorresponding to tubing section I43 and carrying packer I54 (Fig. 14). Apin I55 fixed in sleeve I cooperates with a slot I56 cut in tubing I43to permit a limited relative movement of tubular section I43 and sleeveI60. Lowering tubing section I43 and packer I55 with respect to tubularsleeve I50 releases springs I51 and uncovers inlet ports I45 at the sametime. Insulated leads I51. I58 connect the identifier units I52, I53with the switching unit 51 shown in Figure 14.

Below the bottom tubing section I44 is a section of tubing I59 havinginsulating sleeves I10, I1I with metallic band electrodes I12, I13mounted thereon. A resistance I18 is connected between electrodes I12,I13 by insulated leads, and the upper of these electrodes I12 isconnected by. an insulated lead I19 to one terminal in switching unit51. The bottom end of tubing I59 is equipped with a sliding sleeve I14having ports I15 and slot I15, which cooperates with a pin I11 set intubing I59 to limit the relative vertical movement of valve sleeve I14and tubing I59.

In Figure 16 I have shown'an electrical wiring diagram suitable for usein this embodiment when two identifier units are being used at each setof tubing ports. For purposes of illustration it will be assumed that afluid conductivity cell. and either a fluorescence or an absorption cellare being used together. In this circuit both the surface electricalequipment and that enclosed in switching unit 51 may be identical tothat shown in Figure 4 except that the relay I05 is omitted. In parallelwith each other and with motor I00, so as to be supplied withalternating current, are light sources I80, IIII, I82, I83. Connected byinsulated leads to the various stationary contact points of selectorswitch I02 are photocells I84. I85, I85, I81 and conductivity electrodesI88, I89, I90, I9I hereshowh connected with the switch points inalternating order. although this is immaterial so long as the exactorder is known to the operator. One contact point I92 is connectedbyinsulated lead I19 to metal band electrode I12. I

With this equipment it is possible in a single survey of a well toobtain much more information about the fluid-producing character of theformations than with the other two embodiments. This is done byperforming on the well during the insertion of the tubing 24 and itsassociated equipment a process of permeability logging by which therelative fluid flow resistance of the various formations can bedetermined. As previously pointed out, such information is of greatvalue in the proper carrying out and interpretation of the subsequentfluid-character tests,

11 which primarily indicate the nature the quantity of fluids produced.

[it the start of the survey 'and before the tubing 24 has been loweredto bottom, the well is preferably filled to a point above the topproducing formation with a liquid heavier than oil, such as water orbrine. On top of this body of heavy liquid is a lighter liquid, forexample, oil, immiscible and forming an interface with the brine.Because -of the difference in electrical conductivity of the two fluidsthis interface can be located by the use of. electrodes I12, I13, sinceif both electrodes are immersed in the non-conducting fluid, little orno current can flow through lead I18. If electrode I13 is immersed inthe conducting fluid while electrode I12 is not, then resistance I18 isincluded in the circuit and an intermediate value of current will flowin lead I18; while if both electrodes I12, I13 are immersed in brine,resistance I1! is effectively bypassed and a maximum of current willflow. It is therefore possible to determine with this arrangementwhether the interface between the electrically conducting and thenon-conducting fluids, such as between the oil and the salt water, isbelow, intermediate, or above these electrodes.

Having once located the interface between the fluids in well 2I, it isfollowed by means of electrodes I12, I13 while it is caused to movedownward past the face of the formations by adjusting the input rates ofoil through the annular space between casing 22 and tubing salt waterthrough tubing 24 and out ports I15. By correlating the position andmovement of the interface with the input rates of the two liquids, therelative ability of those formations traversed by the well to take influids can be evaluated, and hence a relative permeability log can bededuced.

When

rather than by the injection or oil or water, or both simultaneously,the interface has been moved through the test region of the well, theintroduction of these fluids is halted, and the apparatus is convertedto one for multiple fluid-character measurements. Whereas in Figure 14the inlet ports I45, I46, I41 were closed so as to direct fluidintroduced into tubing 24 out through ports I15, it will be noted inFigure 17, which shows the apparatus set for a fluid-character test,that this situation is reversed, with ports I15 closed 24 and of' 12shows no further changes, and the well has therefore settled down to asteady-state production.

From the foregoing description it can be seen that by carrying out boththe permeability and the fluid-character determinations as two parts ofa single operation with the same apparatus, information of a far greatervalue is obtained than could be derived from either determination alone.That is, knowledge of the quantity of fluid entering a well at a givendepth is only of limited value if it is not known whether the fluid isgas, oil, or water. Conversely, knowledge of the depths at which gas,oil,,water, or mixtures of them enter, while in itself of very greatvalue, is enhanced by knowing how much of each may be produced at eachdepth interval. With the complete information available from a singletesting operation carried out as remedial work to reduce gas-oil orwater-oil ratios can be undertaken with assurance that the well will notbe damaged. For example, plugging back to shut off water entering thebottom part of a well by dumping or squeezing cement in that part can becarried out in a single step because the operator will have determinedin advance exactly which part or how much of the formation needs to besealed oil. This is a great improvement over the trial and error methodnow employed where several batches of plugging ma-' terial are placed insuccession, with a test-following each to see if the quantity of waterentering has been reduced.

With the average depth of oil wells generally increasing it has beenobserved that errors in depth determination can and do become great 7enough to be serious, and damage is done by and the inlet ports I45,I46, I41 opened. This changeover is accomplished simply by lowering theapparatus and allowing it to rest upon the bottom of the well, sinceupon reaching the bottom, valve member I14 slides upward closing offports I15. Upon further lowering, packing member I64 is first releasedand expanded by springs I to seal off against the wall of the well andports I." are opened. Further lowering releases packer member I55, andit too forms a seal against the well and ports I46 are opened. Insertingof pump depresses sleeve valve I49 so that openings I94 therein registeropposite the openings I in tubing 24. In this position this embodimentoperates exactly as the embodiments of Figures 1 and 12.

It should be noted, however, that due to the fact that fluids foreign tothe formations may have been injected into them during the permeabilitysurvey, the production of the welltreatments carried out at thewrongdepth. However, when both the permeability and the fluid-characterdeterminations are performed with the same tubing string and in the samemanner disclosed, it is practically impossible for discrepancies indepth measurement to occur. Further, if the same tubing string is usedfor subsequent remedial work on the well, the practical advantage of theaccurate depth determination isextended.

It is believed apparent that by this method and apparatus a test can bemade of 'a portion of a well producing several different fluids withoutany appreciable interruption in the producing of the well. All that isnormally required is an interruption for the short interval while theapparatus is being lowered to testing positiomafter which the normalwell production can be continued. This apparatus can be controlled atwill and left in place as long as necessary to identify fully the natureof the fluids entering the well at various levels. In the event theresults at one setting or location of the apparatus are ambiguous oruncertain, as, forinstance, if excessive leakage past one of the packersis suspected, the whole device can be-lifted a few inches or feet andthe measurements repeated or continued.-

It is deemed of major importance that the incentive to complete a testas rapidly as possible and often compromise on securing inferior data isalmost completely lacking in this method of testing. The facility ofrepeating or prolonging a test contributes materially to obtaining theaccurate data necessary for effective remedial work.

With the two apparatus embodiments first described this verticalshifting movement would be easy to perform, as in each case the pressureof disclosed.

the packers against the walls of the well need not be so great as toanchor the apparatus in place. With the last embodiment described,however, it would be necessary to prevent the telescoping of the variousindividual sections from closing oif the inlet ports when the device islifted off bottom. This could be done in a variety of ways, such asproviding L-shaped slots for the pins Ill and I65, so that by a combinedlowering and rotating movement the various members could be telescopedand then locked in the desired position for testing. Thereafter theywould remain in testing position whether the device was resting onbottom or not.

Although a switching device has been suggested for transmitting to thesurface in succession the indications of the respective identifyingunits, it will be understood that a multiple-conductor cable could beprovided such that each unit is connected individually to a surfaceindicating instrument.

Other variations and modifications can be utilized at the will of theoperator, and numerous prior art devices can be modified to assist incarrying out this invention. It is to be understood that the inventionis not limited to the particular apparatus described in detail in thisspecification but is best defined by the scope of the appended claims.

I claim:

1. Apparatus for testing wells comprising a tubing having a plurality ofvertically spaced ports therein and adapted to be lowered into a wellbore, means carried by said tubing for partitioning a producing zone ofsaid well bore into a plurality of isolated sections with at least oneof said ports opening into each of said sections, means attached to saidtubing for simultaneously producing into each of said sections fluidsfrom the well formations exposed in that section and for withdrawingsaid fluids through said ports into a single common stream within saidtubing for removal from said producing zone, and fluidtesting meanscarried by said tubing to identify the fluids entering eachof saidsections from the exposed well formations therein before said fluidsbecome commingled inside said tubing with fluids from others of saidsections during the removal of the fluids from said producing zone.

2. Apparatus for testing wells comprising a tubing having a plurality ofvertically spaced ports therein and adapted to be lowered into a wellbore, partitioning means carried by said tubing for sub-dividing aproducing zone of said well bore into a plurality of isolated sectionswith at least one of said ports opening into each of said sections, pumpmeans within said tubing for simultaneously producing into each of saidsections fluids from the well formations exposed in that section and forwithdrawing said fluids through said ports into a single common streamwithin said tubing for removal from said producing zone, andfluid-testing means carried by said tubing to identify the fluidsentering each of said sections from the-exposed well formations thereinbefore said fluids become commingled inside said tubing with fluids fromothers of said sections during removal of the fluids from said producingzone.

-3. Apparatus for determining the location of ingress of each of aplurality of fluids produced by a well comprising a tubing adapted to belowered into a well and having a plurality of longitudinally spacedopenings 'therein disposable within a producing zone of said well,resilient *well packer means carried by said tubing' and disoutside ofsaid tubing near each of said openings for identifying said fluidsbefore they become intermingled with fluids from others of saidopenings.

4. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubing adapted to be lowered intoa well and having a plurality of longitudinally spaced openings thereindisposable within a producing zone of the well, radially expansibleresilient well packer means carried by said tubing between pairs of saidopenings, means for expanding said well packer means into contact withthe wall of the well, and fluid testing means on the outside of saidtubing near each of said openings for sensing a characteristic ofproduced well fluids.

5. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubing adapted to be lowered intothe well and having a plurality of longitudinally spaced openingstherein disposable within a producing zone of said well, fluidexpansible well packer means carried by said tubing between pairs ofsaid openings, means for supplying fluid under pressure to expand saidwell packer means into contact with the wall of said well, and fluidtesting means for sensing a characteristic of produced well fluids onthe outside of said tubing near each of said openings.

6. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubing adapted to be lowered intothe well and having a plurality of longitudinally spaced openingstherein disposable within a producing zone of said well, radiallyexpansible resilient well packer means carried by said tubing betweenpairs of said openings, releasable spring means for, expanding said wellpacker means radially into contact with the walls of said well, andfluid testing means near each of said openings for sensing acharacteristic of produced well fluids.

7. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubing adapted to be lowered intoa well and having a plurality of longitudinally spaced openings thereindisposable within a producing zone of said well, fluid testing meansnear each of said openings for sensing a characteristic of produced wellfluids, and resilient well packer means carried by said tubing betweenpairs of said openings, each of said packer means comprising a pluralityof closely-s aced parallel concentric flexible disks of varyingdiameters.

8. Apparatus for determining the location of ingress of each of aplurality of fluids produced by a well comprising a tubing adapted to belowered into a well and having a plurality of longitudinally spacedopenings therein disposable within a producing zone of said well, wellpacker means carried by said tubing between pairs of said openings, andfluid testing means on the outside of said tubing and immediatelyadjacent each of said openings forsensing a characteristic identifyingthe produced well fluids passing to said opening before interminglingwith fluids passing to other openings.

9. Apparatus for determining the location of ingress of each of aplurality of fluids produced by a well comprising a tubing adapted to belowered into a well and having a plurality of longitudinally spacedopenings therein disposable within a producing zone of said well, wellpacker means carried by said tubing between pairs 01' said openings,fluid identifying means adjacent each of said openings for sensing acharacteristic of produced well fluids passing to said opening betoreintermingling with fluids passing to other openings, and means fordirecting the flow of said well fluids close to said fluid identifyingmeans. I

10. Apparatus for determining the location of ingress andcharacter offluids produced by a said opening, one of said testing means at eachopening being responsive to a flrst fluid property, and another of saidtesting means at said opening being responsive to a second fluidproperty, whereby fluids not identified by said flrst property may beidentifled.

11. Apparatus for determining the location of ingress of each-of aplurality of fluids produced bya well comprising a tubing adapted to belowered into a well and having a single opening near the bottom endthereof, fluid identifying means adjacent said single opening, aplurality of testing units coupled together and to the bottom end ofsaid tubing below said single opening, each of said units comprising atubular member having an opening therein and carrying a single wellpacker means above said opening and fluid identifying means adjacentsaid opening for sensing, a characteristic of produced well fluidsbefore they enter said opening.

12. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubing adapted to be lowered intoa well and having an initially closed opening near the bottom endthereof. fluid-testing means adjacent said opening, means for removingthe closure from said opening, a plurality of units coupled together andto the bottom end of said tubing below said initially closed opening,each of said units comprising a tubular member carrying aradially-extendable well-packer means and a fluid-testing means adjacentan initially closed opening in said tubular member below said packer, atubular sleeve surrounding the lower portion of said tubular membercovering said opening and holding said packer means retracted, thetubular sleeve of each unit being movable for a limited distance on saidtubular member and being coupled to the tubular member of the next lowerunit, said initially closed openings being opened and said packer meansbeing extended on each unit in turn by the limited movement of eachsleeve relative to the tubular member it surrounds, upon lowering ofsaid tubing 16 and coupled units, with the sleeve of the lowermost ofsaid units in contact with the bottom of said well and the sleeves ofsuccessively higher units being held stationary by the sleeves of lowerunits having reached the limit of their permitted movement.

13. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubing adapted to be lowered intoa well and having a plurality of longitudinally spaced openings thereindisposable within a producing zone of said well, fluid testing means onthe outside of said tubing adjacent each of said openings for sensing acharacteristic of produced well fluids, well packer means carried bysaid tubing between pairs of said openings, said packer means beingexpansible into contact with the wall of said well by fluid pressure,means for supplying fluid under pressure to expand said packer means,and valve means for controllably releasing the pressure fluid to deflatesaid packer means.

14. Apparatus for determining the location of ingress and character offluids produced by a well comprising a tubingadapted to be lowered intoa well and having a plurality of longitudinally spaced openings thereindisposable within a producing zone of said well, well packer meanscarried by said tubing between pairs of said openings, and meansadjacent each of said openings for sensing the electrical conductivityof produced well fluids before said fluids become intermingled with thefluids entering said tubing at another of said openings.

LLOYD E. ELKINS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 46,860 Moulton Mar. 14, 18651,406,682 Rathbone Feb. 11,1922 1,652,472 Erwin et al. Dec. 13, 19271.746,616 Sounitza Feb. 11, 1930 1,889,889 Ennis Dec. 6, 1932 1,956,694Parrish May 1, 1934 2,080,736 Nixon et a1. May 18, 1937 2,218,155 Rusleret al Oct. 15, 1940 2,228,623 Ennis Jan. 14, 1941 2,248,982 GillberghJuly 15, 1941 2,295,738 Gillbergh Sept. 15, 1942 2,334,475 Claudet Nov.16, 1943 2,341,745 Silverman et al Feb. 15, 1944 2,364,957 Douglas Dec.12, 1944 2,376,878 Lehnhard May 29, 1945 2,377,501 Kinley June 5, 19452,413,435 Courter Dec. 31, 1946 r 1 OTHER REFERENCES PetroleumDevelopment and Technology," pages 223-231, vol. 155.

